davidm@uunet.UU.NET (David S. Masterson) (03/22/91)
>>>>> On 12 Mar 91 21:23:14 GMT, saxena@motcid.UUCP (Garurank P. Saxena) said:
Garurank> We are developing CASE tools which have complex relationships
Garurank> between the entities and attributes on relationships.
Garurank> We are looking for a database which supports the Entity-Relationship
Garurank> (ERA ) model. Other requirements from the database would be
Garurank> support for large volumes of data, transaction support, schema
Garurank> evolution etc.
Garurank> Are there commercial or prototype ER databases available?
Isn't ER just a modeling for relational databases? Therefore, don't all
relational databases support the ER(A) model by definition? BTW, what do you
mean by "schema evolution"?
--
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David Masterson Consilium, Inc.
(415) 691-6311 640 Clyde Ct.
uunet!cimshop!davidm Mtn. View, CA 94043
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"If someone thinks they know what I said, then I didn't say it!"holliday@csgrad.cs.vt.edu (03/24/91)
In article <CIMSHOP!DAVIDM.91Mar21135349@uunet.UU.NET> cimshop!davidm@uunet.UU.NET (David S. Masterson) writes: >>>>>> On 12 Mar 91 21:23:14 GMT, saxena@motcid.UUCP (Garurank P. Saxena) said: >Garurank> We are looking for a database which supports the Entity-Relationship >Garurank> (ERA ) model. Other requirements from the database would be > >Garurank> Are there commercial or prototype ER databases available? > >Isn't ER just a modeling for relational databases? Therefore, don't all >relational databases support the ER(A) model by definition? BTW, what do you >mean by "schema evolution"? >David Masterson Consilium, Inc. No - ERA is often used to help design relational layouts, but these methods end up converting from ERA to relational tables. As data models, they are 2 different things. I am only aware of 2 full-fledged ERA databases. One is PSA, from MetaSystems, Ann Arbor. It's been sold in various forms since the 70s, descending from ERA research at U of Mich, and shows its age. The second is Camera, from ASTEC in Greenbelt MD, which is marketed as a direct competitor to PSA. -- Glenn | holliday@csgrad.cs.vt.edu OR Holliday | glenn%bayberry@chado.fidonet.org OR | GHOLLID@access.nswc.navy.mil (Internet)